Microphone



March 8, 1938. GERLACH 2,11Q763 I MICROPHONE Filed March 14, 1936 INVENTOR ERWIN GERLACH ATTORNEY Patented Mar. 8 1938 UNITED STATES PATENT'OFFICE MICROPHONE Erwin Gerlach, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphie m. b. H., Berlin, Germany, a. corporation of Germany Application March 14, 1936, Serial No. 68,788

1 In Germany March 14, 1935 6 Claims. (Cl. 179-148) This invcntionrelates to an improved micropacity has a very small value. The acoustic phone upright or support. field around the microphone is only slightly dis-- In condenser microphones with an upright or torted. support capable of adjustment in level or height, The inner conductor is attached at the top of 5 the amplifier, as a rule, is mounted at close the up t- At t e bottom base end it is proximity to the microphone in order that the placed on a roller, pulley, or the like, made from connection between the latter and the amplifier insulation material. This pulley should involve may be as short as possible. In fact, one prea minimum amount of capacitance, in order that ferred scheme is to secure the amplifier directly no spurious capacitive actions may arise. When 10 on the upright or support below the microphone. the upr is extended. the Wire Will unwind The cable brought away from the amplifier, in from the pulley or spool. At the same time a one of the forms of construction disclosed in the spring engaging the said spool or pulley and earlier art, is disposed on the outside of the upwhich may act as a current supply lead becomes right. It thus produces always a lateral pull tensioned. But if the up t s t c p upon the upright or support, and this tends to get e Spring Will bechme Slack and the make the latter less stable and steady. pool is pul ed by it in the opposite i ti so It is also known in this form of construction that the wire will be wound up. to accommodate leads interiorly of the upright. One exemplified embodiment of the invention When adjusting the height of the upright, the is shown in the annexed drawing. Upon the base 20 cable must be shifted out or in at the bottom piece I is mount d a tubular upright Shift 20 end of the upright. The leads are thus subject ably disposed inside tube 2 is the tube 3, and it to a good deal of wear and tear, in fact, they may be locked in the desired position by the aid chafe and wearfast. Also in types of upright of a ring 4 and a screw 5. On one of the tubular in which the leads are fixed at the bottom end, leads is arranged conveniently a slide contact in and in which the wire in the upright is coiled or Order th a good electrical Connection ay all 25 kinked irregularly, trouble is often encountered the time be insured between the extensible orv for the reason that the leads are markedly bent telescoping tubes when the heig t of e up and wear quickly at the kinks. is adjusted. In lieu of the ring and screw for All of these constructions in which the amlocking and retaining the device in the desired plifier is disposed directly underneath the microand adjusted position, there could be used also a 30 phone and secured on the upright, involve an adcan s The end 0f the tube Where t p ditional drawback which inheres in the very screw is engaged, is split more or less deeply at type thereof: The acoustic field about the micro- 'a number of places. This part of the tube will phone is seriously disturbed by the amplifier. then yieldingly engage around the other tube,

Now according to the present invention such and will assure good electrical union also when 35 difliculties and drawbacks in reference to the loosening the cap screw. acoustic field as are found in extensible types of On top of the tube 3, in a ball and socket joint uprights for condenser or electrostatic micro-, 6 is fitted the condenser microphone I in a way phones known in the prior art are cured by that so as to be capable of being easily turned in all 40 the upright or support consists of telescoping directions and being thus adjustable. In the cen- 40 tubes which at the same time constitute an electer of the upright the lead or conductor 8 is districal lead for the microphone. The other supposed upon spacer pieces 9. These spacer pieces ply lead is accommodated inside, andinsulated 9, if desired, may be coated with a thin coat of from, the tubular support or upright by means parafiin. The latter is heated to temperatures of spacer pieces and thus connected to the microover 100 degrees C., and the spacers are immersed 45 phone; it is formed so as to be reeled or wound up. in the liquefied parafiin for a while. By this This inside conductor consists of a wire of comtreatment the insulation power of the spacers is paratively small diameter. The distance between essentially increased, particularly if the microthe outer and the inner conductor must be chosen phone standard is to be used for outdoor work.

in such a way that a cable of the lowest possible In order that the parafiln may be made to stick 5|) capacitance results. Changes in the cable capacfirmly upon the surface, the latter preferably is ity values of the leads, when the height of the provided wi h flutes 0r r v o is r h n upright is altered, are practically unnoticed in or a at d in some other mannerreference to the sensitivity or in the frequency The wire 8 is wound upon a pulley or spool l0 5 response, for the reason that the conductor caaccommodated in the bottom end I of the upright. Engaging the pivot ll of the spool III is the spring II, which, if necessary, in an insulated manner is secured in the base, say, at the point marked l3. The conductor 8 has one end united with a transmission line or circuit (not shown in the drawing), while the other end is brought to one of the terminals of the condenser microphone. The respective other electrode or terminal of the said condenser microphone is united with the upright 2 and 3, the latter, in turn, being grounded.

In lieu of the spring there could be used also a springor weight-loaded pulling device.

The microphone amplifier could be disposed either below and directly on the foot or base I of the upright, or else be mounted separately from the upright. i

I claim:

1. An adjustable support for a condenser microphone comprising a plurality of metallic tubular members arranged to telescope within each other to provide adjustment in the height of said microphone support, said metallic members serving as one conductor of said microphone circuit, a wire centrally located within said metallic tubular members and serving as the other conductor of said microphone, a base member supporting said tubular members, a pulley of insulating material located within said base'inember so as to present the lowest possible capacitance in the microphone circuit.

2. An adjustable support for a condenser microphone comprising a plurality of metallic tubular members arranged to telescope within each other to provide adjustment in the height of said microphone support, said metallic members serving as one conductor of said microphone circuit, a wire centrally located within said metallic tubular members and serving as the other conductor of said microphone, and a plurality of insulating spacing members located within at least one of said metallic tubular members for retaining said other conductor concentrically within said tubular members.

3. An adjustable support for a condenser microphone comprising a plurality of metallic tubular members arranged to telescope within each other to provide adjustment in the height of said microphone support, said metallic members serving as one conductor of said microphone circuit, a wire centrally located within said metallic tubular members and serving as the other conductor of said microphone, a plurality of insulating spacing members which are paraflln coated located within at least one of said metallic tubular members for retaining said other conductor concentrically within said tubular members.

4. An adjustable support for a condenser microphone comprising a plurality of metallic tubular members arranged to telescope within each other to provide adjustment in the height of said microphone support, at least one of said tubular members split to provide a yieldingly engaging slide contact, said metallic members serving as one conductor of said microphone circuit, a wire centrally located Within said tubular members and serving as the other conductor of said microphone, a base member supporting said tubular members, and a pulley of insulating material located within said base member so as to present the lowest possible capacitance in the microphone circuit.

5. An adjustable support for a condenser microphone comprising a plurality of metallic tubular members arranged to telescope within each other to provide adjustment in the height of said microphone support, at least one 01' said tubular members having a clamping device to retain said metallic members in a fixed position, said metallic members serving as one conductor of said microphone circuit, a wire centrally located within said tubular members and serving as the other conductor of said microphone, a base member supporting said tubular members, and a pulley of insulating material located within said base member so as to present the lowest possible capacitance in the microphone circuit.

6. An adjustable support for a condenser mlcrophone comprising a plurality of metallic tubular members arranged to telescope within each other to provide adjustment in the height of said microphone support, a ball and socket joint located at the top end of one of said tubular members for adjustably securing said microphone to said support, said metallic members serving as one conductor of said microphone circuit, a wire centrally located within said metallic tubular members and serving as the other conductor of said microphone, a base member supporting said tubular members, and a pulley of insulating material located within said base member so as to present the lowest possible capacitance in the microphone circuit.

ERWIN GERLACH. 

